I’m gonna have to agree with @Thunderbird on this one, @The_Justifier. Although I don’t think literally turning into air is the way to go with Shu, flight, invisibility, and intangibility seem entirely doable with comic book science. Yes, it probably wouldn’t work out too well in our world, but comics never cared about that. The Flash has been vibrating through things for upwards of 60 years. It’s Artistic License.
All of those definitely work. I’m not quite sure what to do with Isis either. Maybe just give her flight and energy blasts? Or perhaps telekinesis, as that’s pretty magical-looking. I don’t think technopathy is the way to go with her, as that would be of very limited use in a fantasy setting.
Nuit, as “She Who Protects,” should probably get force-shields. Tefnut could have either some enhanced combat claws or maybe something that pulls moisture from the air and then releases it in a high-pressure blast. I don’t really know what Universe 1 Osiris’s powers are, but he deals psychic damage so he could just have a psychic disrupter of some sort.
Regarding those nutty X-Men, Colossus is far from the only one that doesn’t make scientific sense. Iceman has a similar problem, as a person made of literal ice is not a person anymore. Angel’s wings should not be able to lift him. And so many of them violate the Law of Conservation of Mass and Energy: Cyclops, Jean Grey, Professor X, Banshee, Magneto, Havok, Gambit, Jubilee, Wolverine, et cetera.
Also, while on the topic of the Celestial-Mutant connexion, I recommend Earth X, which is an excellent What If? story that heavily features the concept.